[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18

[blowfish]

Seems like FAR is giving up on life. On win32, and there seems to be no aerodynamics-ish. Parachutes still work, but drag does not exist aside from that.

You did install ModularFlightIntegrator, didn't you?

[BudgetHedgehog]

Seems like FAR is giving up on life. On win32, and there seems to be no aerodynamics-ish. Parachutes still work, but drag does not exist aside from that.

Also, seen the known issue on Github. Nail solid reproduction steps and help squash this.

[Solar71]

Playing devils advocate again, it is totally legit however to change some settings to make the game more enjoyable for yourself.

But increasing the viscosity of air by three order of magnitude and saying it feels more realistic, is going to raise an eyebrow. Sure subjectively it may feel better but Ferram4 cannot please everyones subjective feelings. The goal is to make FAR as realistic as possible according to hard real world measured data.

Lol. Yea. You would think that.

Actually I did as well. I thought changing the numbers would make a bigger difference. But in actuality.

If im remembering correctly, it used to take something like 3800 DV to get into low kerbin orbit.

But after making the changes, it was taking about 4700 DV.

That's a substantial amount more. But not three orders of magnitude.

not sure exactly why, maybe atmospheric viscosity has a smaller effect than we think ?

ps: it's not just rockets. Airplanes slip through the atmosphere at sea level far too easily as well.

Planes do t normally NEED air brakes to get below 200 mph.

But with far is seems like you need them. Even for a light weight single seater jet.

[blowfish]

ps: it's not just rockets. Airplanes slip through the atmosphere at sea level far too easily as well.

Planes do t normally NEED air brakes to get below 200 mph.

But with far is seems like you need them. Even for a light weight single seater jet.

You could always, you know, decrease the throttle to zero and increase the length of your approach run. Isn't that what happens for real planes?

[OvermindDL1]

Reporting an exception that happens a few times on loading in location:

FerramAerospaceResearch.FARPartGeometry.GeometryModification.StockJettisonTransformGeoUpdator..ctor

[Solar71]

You could always, you know, decrease the throttle to zero and increase the length of your approach run. Isn't that what happens for real planes?

Lol. You're funny.

Offcourse I cut throttle to zero.

A looooooong way before the runway begins.

But the plane scrubs speed too slowly without air brakes or flaps.

Real life, single engine planes don't need flaps to slow down. They use flaps primarily to create lift.

This is done to lower stall speed.

But in general is not used as a brake. Even though it has that secondary effect.

Either way. I will either mod/fix fars's physics to my liking. It just stop using it all together.

In fact I don't even care if far is fixed by the dev. All I care about is being able to mod it myself.

But right now that's buggy as well. Since changes don't always stick. Ah well.

[Littlerift]

Airplanes slip through the atmosphere at sea level far too easily as well.

Planes do t normally NEED air brakes to get below 200 mph.

But with far is seems like you need them. Even for a light weight single seater jet.

This isn't even remotely true. If you bring the throttle down then a craft built for FAR can easily drop to, and maintain, below 200 MPH.

Edit: Wait, this is for landing? Okay, I'm going to go ahead and say that you aren't giving yourself enough space to land. With a real jet aircraft a short final approach could easily still be 4 or 5 nautical miles, and that's starting from a speed of only around 250MPH. If you consider how tiny Kerbin is, a similar approach on Kerbin is a long way off from the runway.

Edited June 11, 2015 by Littlerift

[blowfish]

If you're not slowing down by the time you get to the runway, you're not cutting the throttle soon enough.

[steve_v]

Dude, seriously? many of my designs have no airbrakes, spoilers or flaps. The are capable of flight well below 200mph and, unsurprisingly, quite land-able.

"scrubs too slowly" by whose standards? you got numbers to back that up? I only put flaps and spoilers on large aircraft or those designed primarily for supersonic performance. No problem at all with small subsonic planes.

As you say, small craft shouldn't need airbrakes to slow down... and they don't, if you take a sensible approach.

Are you moaning about drag because you want the old (pre 1.0) soup-o-sphere back, by any chance? If so you're SOL, that system was so broken it's not funny and asking ferram to do that to FAR is almost an insult.

"I want to change some constants and see what happens" is just fine, but "FAR is broken and I need this feature so I can 'fix' it" implies that you know better than the dude that wrote the thing. Step up or shut up.

If you want a treacle atmosphere, knock yourself out. Just don't insist it's an improvement, and everyone else has got it wrong. Unless of course you can back it up, with math and citations.

[Solar71]

If you're not slowing down by the time you get to the runway, you're not cutting the throttle soon enough.

Hmm. Ok. I guess I can cut throttle even sooner.

But im already pretty far from kps when I do. But I can try even further.

My goal is to land at around 90-100 mph.

40-45 m/s. I find it very difficult to get that slow without air brakes on my little single seater jet.

ps: I made a mistake earlier. I meant 100 mph. Not 200.

So. About 45 m/s. Not 90 m/s

Edited June 11, 2015 by Solar71

[Littlerift]

90-100mph is really rather slow when compared to the landing speed of modern, single-engined, jet aircraft.

[Kagame]

Um, Mk. 2 cargo bays respond to the cross-sectional area curve and the other curve (the yellow one) as if they were open 100% of the time. I've had this problem with the OPT cargo bays as well, but the Mk. 3 cargo bays work just fine. Is there any rhyme or reason to this, and is it a known issue? I can't be the only person taking cargo into orbit with nuFAR.

Pic proving I'm not insane:

Edited June 11, 2015 by Kagame

[Solar71]

90-100mph is really rather slow when compared to the landing speed of modern, single-engined, jet aircraft.

it is?

Hmm. I always thought non military, small single engine jet aircraft landed at about that speed.

Assuming neutral conditions. No head, tail, or crosswinds.

now fighter jets might typically land at higher speeds? Like an F16? Maybe because it's a little heavier.

So what speed would you say is typical for landing if not 90-100 mph? 150? 180?

[Spartan-S63]

Dude, seriously? many of my designs have no airbrakes, spoilers or flaps. The are capable of flight well below 200mph and, unsurprisingly, quite land-able.

"scrubs too slowly" by whose standards? you got numbers to back that up? I only put flaps and spoilers on large aircraft or those designed primarily for supersonic performance. No problem at all with small subsonic planes.

As you say, small craft shouldn't need airbrakes to slow down... and they don't, if you take a sensible approach.

Are you moaning about drag because you want the old (pre 1.0) soup-o-sphere back, by any chance? If so you're SOL, that system was so broken it's not funny and asking ferram to do that to FAR is almost an insult.

"I want to change some constants and see what happens" is just fine, but "FAR is broken and I need this feature so I can 'fix' it" implies that you know better than the dude that wrote the thing. Step up or shut up.

If you want a treacle atmosphere, knock yourself out. Just don't insist it's an improvement, and everyone else has got it wrong. Unless of course you can back it up, with math and citations.

On a side note, I have a shuttle design that cruises in at 200+ m/s before landing. The only way I could bring the speed down to 90-100 m/s (which is still a tad too fast) is by using differential flaps. I have one set deflect upwards and the other set defect downwards. It effectively works as inline spoilers that also function as control surfaces. It works out pretty well, actually.

[steve_v]

Sounds like it flies as a shuttle should... fast and brick-like.

[Solar71]

I think I either found the problem with my FAR or I just found a new bug.

Ok here goes.

You know that screen that shows a yellow line and a green line...

Sort of squiggly... Well mine used to be squiggly too... Depending on design of craft, sometimes more squiggly then other...hahaha

Well I tried to modify FAR again today and I keep hitting the ground at 465 m/s with just an MK1 capsule.

None of my parachutes can survive this. They open for about 1 second. Then they snap off and my kerbal dies.

This is a simple rocket. 2,044 Dv... goes up to about 80k then straight back down. (Suborbital)

So I try to see whats going on... I click the button to show me the squiggly lines along the outside of my ship...

They both pop up. but are PERFECTLY straight. Yellow and green perfectly straight in a vertical direction.

When I hit the debug button to show the little pink voxels or whatever they're called. they show up... just like normal...

But the squiggly lines are totally straight.

Could this be why FAR is not responding to my changes to the FARAeroData.cfg ???

thanks

I hope this link works

http://steamcommunity.com/sharedfiles/filedetails/?id=459033694

Edited June 11, 2015 by Solar71

[futrtrubl]

That's a substantial amount more. But not three orders of magnitude.

not sure exactly why, maybe atmospheric viscosity has a smaller effect than we think ?

That's exactly what Ferram said

A much larger influence in this is air density. Most of the forces that set terminal velocity (wherever it may be) are dominated by air density, with little to no direct influence from viscosity. If the setting did save, you'd be in hre complaining that it didn't do anything because your changes, in the grand scheme of things, really don't change anything. Besides high altitude drag, that'll be a fair bit higher.

[Solar71]

That's exactly what Ferram said

Yes, that's what it seems like to me.

Did you look at the pic I posted?p by chance?

any idea why Far thinks my rocket is a perfectly aerodynamic object? Lol

just kidding, it looks more like Far is not seeing the craft at all.

Any idea as to why?

thanks

[Bakase]

Hmm. Ok. I guess I can cut throttle even sooner.

But im already pretty far from kps when I do. But I can try even further.

My goal is to land at around 90-100 mph.

40-45 m/s. I find it very difficult to get that slow without air brakes on my little single seater jet.

ps: I made a mistake earlier. I meant 100 mph. Not 200.

So. About 45 m/s. Not 90 m/s

It might depend on what craft you're using, but I have absolutely no trouble slowing down. If you're having particular trouble with an aircraft, post pictures. It's probably a problem with your design or piloting, rather than the aerodynamic simulation. Could be that your craft is unrealistically heavy.

If, by chance, there is something going wrong with the simulation, you've helped fix something. But until you show that an aircraft exhibits truly unrealistic behaviour, backing this up with data, don't assume the maths behind the program is at fault.

Um, Mk. 2 cargo bays respond to the cross-sectional area curve and the other curve (the yellow one) as if they were open 100% of the time. I've had this problem with the OPT cargo bays as well, but the Mk. 3 cargo bays work just fine. Is there any rhyme or reason to this, and is it a known issue? I can't be the only person taking cargo into orbit with nuFAR.

Pic proving I'm not insane:

http://i.imgur.com/3vWIkop.jpg

This is an issue in Ferri. Fixed in the current devbuild.

I think I either found the problem with my FAR or I just found a new bug.

Ok here goes.

You know that screen that shows a yellow line and a green line...

Sort of squiggly... Well mine used to be squiggly too... Depending on design of craft, sometimes more squiggly then other...hahaha

Well I tried to modify FAR again today and I keep hitting the ground at 465 m/s with just an MK1 capsule.

None of my parachutes can survive this. They open for about 1 second. Then they snap off and my kerbal dies.

This is a simple rocket. 2,044 Dv... goes up to about 80k then straight back down. (Suborbital)

So I try to see whats going on... I click the button to show me the squiggly lines along the outside of my ship...

They both pop up. but are PERFECTLY straight. Yellow and green perfectly straight in a vertical direction.

When I hit the debug button to show the little pink voxels or whatever they're called. they show up... just like normal...

But the squiggly lines are totally straight.

Could this be why FAR is not responding to my changes to the FARAeroData.cfg ???

thanks

I hope this link works

http://steamcommunity.com/sharedfiles/filedetails/?id=459033694

What in hell have you done? If you want support with that, you're going to need to post exactly what modifications you made... Even so, I don't think anybody's really going to bother helping you with that. It looks to me like you've totally screwed things up in the cfg and changed something you're not meant to -- the voxels look wrong as well.

[hirschhornsalz]

I just stopped by to tell you that this is a great mod, and you are doing an extraordinary job, Ferram.

Just ignore the few, but very vocal idiots, who try to explain you that you are doing everything wrong because you don't have a clue about aerodynamics and stuff ;-)

http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect

[Littlerift]

it is?

Hmm. I always thought non military, small single engine jet aircraft landed at about that speed.

Assuming neutral conditions. No head, tail, or crosswinds.

now fighter jets might typically land at higher speeds? Like an F16? Maybe because it's a little heavier.

So what speed would you say is typical for landing if not 90-100 mph? 150? 180?

I don't know the exact speeds for modern light commercial jets, but I do know that the pilot's manual for the Spitfire Mk IX recommended an approach speed (on a plane with full fuel but no ammunition) of around 100mph with flaps down. If you assume that the pilot flares the plane lightly before landing, you could maybe say that the touchdown speed would be around 90mph. I would be surprised if modern light jets are landing at the same speed as a low wing-loading propeller aircraft which lacks airbrakes.

However, within the realms of KSP, SAS enables you to lower the workable landing speed, so long as you have low enough wing-loading and effective control surfaces. I don't really understand how anybody could have difficulty landing in FAR even at 100m/s, unless you're designing a very unstable craft. Perhaps you should post some pictures of the craft you're trying to land (although I would suggest doing so in the FAR craft repository and not clogging up this thread even more with craft issues).

Edit: although given the image you posted up above, I think the best bet for you is to wipe FAR from your game data and reinstall it. I have no idea what you've done, but you've clearly wrecked the viability of the .cfg you're using.

[mossman]

It seems like this rocket is less stable when fairings are covering the payload than not. Any idea what could be going on here? As far as I can tell the parts in the fairings are being shielded correctly.

[kcs123]

It seems like this rocket is less stable when fairings are covering the payload than not. Any idea what could be going on here? As far as I can tell the parts in the fairings are being shielded correctly.

http://puu.sh/ikQZS/ebc23154d7.jpg

http://puu.sh/ikQYv/e4fcb82d69.jpg

Why you think that this rocket is less stable with fairings ?

Based on provided pictures, rocket on first picture will be unstable. Without pilot input, aerodynamic and gravity forces combined will tend to bend this rocket towards positive AoA.

It is desired situation for planes that flies horizontaly, but it is not something that you wish for rocket.

Second picture shows that aerodynamic and gravity forces combined will point rocket in zero AoA. It means it will be in center of your prograde vector all times without input from pilot.

When you want to steer this rocket, after you finish your turn it will be stable in center of your prograde vector. Desireable thing for rocket design, in area where you have least amount of drag.

Rockets tends to use power of their engines, not wing lifting surfaces, so for rocket designs winglets are just sometimes unavoidable weight to have more controlable rocket if engine gimbals are not enough.

[taniwha]

mossman: look at the cross-section area (just with your eye): without the fairing, the cross section area of the nose area is fairly small compared to the rest of the rocket: there's less surface on which the air can act. The fairing extends the large cross section area nearly to the tip of the rocket, so it will become less stable (though perform much better in the transonic region).

Your payload is very light and your rocket is very short: this is a very difficult combination to make stable.

[mossman]

Why you think that this rocket is less stable with fairings ?

Based on provided pictures, rocket on first picture will be unstable. Without pilot input, aerodynamic and gravity forces combined will tend to bend this rocket towards positive AoA.

It is desired situation for planes that flies horizontaly, but it is not something that you wish for rocket.

Second picture shows that aerodynamic and gravity forces combined will point rocket in zero AoA. It means it will be in center of your prograde vector all times without input from pilot.

When you want to steer this rocket, after you finish your turn it will be stable in center of your prograde vector. Desireable thing for rocket design, in area where you have least amount of drag.

Rockets tends to use power of their engines, not wing lifting surfaces, so for rocket designs winglets are just sometimes unavoidable weight to have more controlable rocket if engine gimbals are not enough.

The first graph shows a less stable design than the second one since the slope of the yellow cm curve is more positive.

Both are unstable, the second one moreso

mossman: look at the cross-section area (just with your eye): without the fairing, the cross section area of the nose area is fairly small compared to the rest of the rocket: there's less surface on which the air can act. The fairing extends the large cross section area nearly to the tip of the rocket, so it will become less stable (though perform much better in the transonic region).

Your payload is very light and your rocket is very short: this is a very difficult combination to make stable.

Yeah sounds about right. I'd have thought the smooth surface of the fairing exterior would be more aerodynamic subsonic. Is this realistic?

Edited June 11, 2015 by mossman